This invention relates to electro-mechanical machinery and more particularly to such machinery utilizing a disc-type rotor.
Electrical machines, such as motor or generators, utilizing disc-type rotors as well known in the art. Such machines utilizing wires conventionally wound on the disc rotors are frequency unsatisfactory in that the rotors are undesirably bulky and irregular winding arrangements are required. The arrangement of conventional wires into a suitable winding pattern usually results in the cross-over of wires in the magnetic gap thereby resulting in a large gap and a consequential reduction in flux in the air gap.
To overcome the aforementioned disadvantages, printed circuit-type machines in which a conductive pattern is coated on the faces of a thin disc of insulating material to form the armature have been provided. An example of such a printedtype armature can be found in U.S. Pat. No. 2,970,238 issued to Swiggett on Jan. 31, 1961. These types of motors provide a number of advantages. For example, these machines exhibit virtually no magnetic flux distortion and no eddy current induction. The printed circuit armature machines are further advantageous in that they may include a large number of poles without increasing eddy loss and while increasing the back e.m.f. The printed circuit machines, however, suffer from the disadvantage that, when fabricating a high power machine, the thickness of the copper windings must be increased which is difficult to accomplish by etching techniques. Furthermore, the limitations of etching techniques are such that the minimum obtainable separations between armature conductors are on the order of twenty to thirty thousandths of an inch. This of course, limits the number of turns of wire which can be provided in a given area. In addition, etching techniques require thin metal conductors and this increases the resistance of the armature winding. The combination of relatively few turns in a given area combined with relatively high armature resistance results, of course, in a relatively low power machine. A further drawback to the printed circuit armature machine is that, because the conductive pattern is coated on the two faces of the disc-like armature, connections must be made between the conductors on both faces or sides of the disc. This involves clips or pads which extend over the outer and inner peripheral edges of the disc and these clips or pads must be soldered or welded to the conductors. The extremely large number of connectors required adds substantially to the cost of manufacture and, in addition, substantially increases the likelihood of an open circuit (due to a weld or solder failure) in the winding.